Was it scattered or in a box?
Maybe the box or bag fell off a running away thief’s chariot?
Either a pulled disc or plow over the years or air dropped bombs during WWII scattered the coins from it's container.
I would lean towards a plow over the years created the debris field.
I think I left that detail in my somewhat heavy-handed edit job.
As others have pointed out. A plow. The container, either wooden, leather, or cloth rotted away over the millenia. The coins were dispersed throughout the field through the action of frost heaving in the soil and annual plowing